Enhanced dielectric and piezoelectric properties of Mn doped (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3–SrTiO3 thin films

Abstract

Lead free 0.95(0.8Bi0.5Na0.5TiO3–0.2Bi0.5K0.5)TiO3–0.05SrTiO3 (BNT–BKT–ST) + x mol% (x = 0–1.0) Mn thin films were deposited on Pt (1 1 1)/Ti/SiO2/Si substrates by a sol–gel processing technique. The effects of Mn content on the structural, ferroelectric, piezoelectric and dielectric properties of the BNT–BKT–ST thin films were investigated in detail. The BNT–BKT–ST thin films doped with different Mn content exhibit pseudo-cubic perovskite structure and doped with 0.5 mol% Mn exhibits the largest grain size and the best dielectric properties. Reduced leakage current and improved piezoelectric constant (d33) were observed in the Mn doped BNT–BKT–ST thin films. The maximum d33 value of BNT–BKT–ST thin films doped with 0.5 mol% Mn is approximately 93 pm/V, which is comparable to that of polycrystalline PZT thin films. The results indicated that Mn doped BNT–BKT–ST thin films would be of great interest for lead-free piezoelectric devices.